"to produce young from eggs by incubation," from Middle English hachen (early 13c.), probably from an unrecorded Old English *hæccan, of unknown origin, related to Middle High German, German hecken "to mate" (used of birds). Meaning "to come forth from an egg" is late 14c. Figurative use (of plots, etc.) is from early 14c. Related: Hatched; hatching.

"opening," Old English hæc (genitive hæcce) "fence, grating, gate," from Proto-Germanic *hak- (cognates: Middle High German heck, Dutch hek "fence, gate"). This apparently is the source of many of the Hatcher surnames; "one who lives near a gate." Sense of "plank opening in ship's deck" is first recorded mid-13c. Drinking phrase down the hatch first recorded 1931.